Well tools

ABSTRACT

A WELL TOOL SYSTEM, PARTICULARLY ADAPTED TO PRODUCING WELLS BY GAS LIFT, INCLUDING SPACED PARALLEL TUBING STRINGS INTERCONNECTED BY CROSS-OVER ASSEMBLIES FOR INTRODUCING LIFT GAS INTO A WELL THROUGH ONE TUBING STRING AND PRODUCTION OF WELL FLUIDS THROUGH THE OTHER TUBING STRING INDEPENDENTLY OF THE CASING ANNULUS WHICH MAY REMAIN LIQUID FULL DURING THE GAS LIFT PROCEDURE.

P. S. SIZER WELL TOOLS Sept. 20, 1971 3 Sheets-Shoot l Filed Feb. 19,1969 zal l INVENTOR. Phillip S. Sizer Bmymw M ATTORNEY P. S. SIZER WELLTOOLS sept. 2o," 11971 3 Sheets-Shut 3 med Feb. 19; 1969 "Fig F i Q |4INVENTOR.

Phillip S. Sizer BNQ ATTORNEY United States Patent @mee 3,606,584Patented Sept. 20, 1971 3,606,584 WELL TOOLS Phillip S. Sizer, Dallas,Tex., assignor to Otis Engineering Corporation, Dallas, Tex. Filed Feb.19, 1969, Ser. No. 800,539 Int. Cl. F04f 1/18; E21b 43/ 00 U.S. Cl.417-109 26 Claims ABSTRACT OF THE DISCLOSURE This invention relates towell tools and more particularly relates to a well tool systemespecially adapted to production of Wells by gas lift procedures.

It is an object of the invention to provide a well tool system forproducing well fluids from a well.

It is a particularly important object of the invention to provide asystem of well tools for producing wells by gas lift procedures.

It is another important object of the invention to provide a gas liftsystem for a well wherein the well may remain liquid filled around thewell tubing while being produced by gas lift procedures.

It is another object of the invention to provide a gas lift system for awell wherein gas lift valves may be positioned within the main ilowstream of injected lift gas to provide maximum protection to the gaslift and sleeve valves from the produced well fluids.

-It is another object of the invention to provide a gas lift systemwherein gas lift valves may be pumped between a prface installation andoperating locations Within a we It is another object of the invention toprovide a well tool system particularly adapted to a gas lift procedureincluding a pair of well tubing strings for conducting lift gas into awell and removing production lluids from the well.

It is a further object of the invention to provide a gas lift system forwells including spaced parallel tubing strings interconnected by meansproviding communication between the strings to permit injection of liftgas into the well in one of the strings and the recovery of Well iluidsin the other of the strings.

It is another object of the invention to provide a new and improved gaslift system including parallel tubing strings interconnected at selectedlocations along their lengths by H-member cross-over assemblies forsupporting gas lift valves and communicating the injection string withthe production string through the valves.

It is another object of the invention to provide a gas lift system forwells wherein the injection and production flow passages are defined byinterconnected inlet and outlet ow paths through the well which areindependent of the annular space in the well around the well tubingstrings so that the well may be operated with the annular space in aliquid-filled condition.

It is another object of the invention to provide a gas lift systemincluding a gas lift valve adapted to be disposed in an injection gaslift ow passage for controlling the flow of lift gas from a central flowpassage through the gas lift valve to a packed oli annular space aroundthe gas lift valve.

It is another object of the invention to provide a gas lift valve havinga central injection gas flow passage and valve means for controllingflow of the lift gas outwardly to an annulus around the valve.

It is a still further object of the invention to provide a gas liftsystem utilizing a gas lift valve which is compatible with several knownsystems for pumping well tools to` and from operating locations in awell from a surface instalation.

It is still another object of the invention to provide a gas lift systemincluding parallel interconnected tubing strings and a new and improvedtravel-limiting swivel joint for coupling sections of one of the tubingstrings between the cross-over members.

It is still another object of the invention to provide a new andimproved travel-limiting swivel joint for coupling pipe sectionstogether.

It is another object of the invention to provide a gas lift system forwells comprising a pair of interconnected parallel tubing stringswherein a gas lift valve is supported at a landing nipple in theproduction string at the crossover connection with the injection stringand the injection string at such connection has a smooth full-boreopening.

It is another object of the invention to provide a gas lift system ofthe character described wherein a gas lift valve is supported in theinjection string at a cross-over connection and the production stringhas a smooth fullbore opening at the cross-over connection.

It is another object of the invention to provide a gas lift system ofthe character described including a crossover connection providing alanding nipple in both the injection and production strings at theconnection and a gas lift valve is supported in the injection string.

It is another object of the invention to provide a gas lift system ofthe character described including a crossover connection having landingnipples in both the injection and production strings and a gas liftvalve in the production string at the connection.

It is another object of the invention to provide a gas lift system ofthe character described having a cross-over connection provided with alanding nipple and sliding sleeve valve in the production string at theconnection and a landing nipple only in the injection side of theconnection with a gas lift valve locked in the landing nipple in theinjection side.

-It is another object of the invention to provide a gas lift system ofthe character described including a crossover connection having alanding nipple in the production string at the connection, a gas liftvalve locked in the landing nipple in the production side, and a landingnipple including a sliding sleeve valve at the connection in theinjection side.

It is another object of the invention to provide a gas lift system ofthe character described including a cross- Aover connection having alanding nipple in the production side at the connection and a landingnipple with a sliding sleeve valve in the gas injection side `with a gaslitt valve locked within the sleeve valve.

It is another object ofthe invention to provide a gas lift system of thecharacter described including a crossover connection having a smoothfull bore opening in the gas injection side and a landing nipple with asliding sleeve valve in the production side including a gas lift valvesecured through the sliding sleeve valve.

Additional objects and advantages of the invention will be readilyapparent from reading the following description of apparatus constructedin accordance with the invention and by reference to the accompanyingdrawings thereof wherein:

FIG. l is a schematic drawing, partially in section, of a gas liftsystem for a well embodying the invention;

FIGS. 2 and 2A taken together comprise a `detailed longitudinalsectional view of a cross-over assembly for use inthe well system ofPIG. l;

FIG. 3 is a sectional view along the line 3--3 of FIG. 2A;

FIG. 4 is a longitudinal view in section and elevation of atravel-limiting swivel joint used in the well system of FIG. 1;

FIG. 5 is a fragmentary, longitudinal view in section and elevation of agas lift valve and upper and lower seal assemblies for use in a gas liftwell system of the type shown in FIG. 1;

FIG. 6 is a fragmentary, longitudinal view in section and elevation ofapparatus useful with the gas lift valve of FIG. 5 for pumping a gaslift valve into and out of the well system of FIG. 1 and for locking thevalve in operating relationship within one of the tubing strings of thegas lift system;

FIG. 7 is a fragmentary view in section of one arrangement of across-over assembly in the system of FIG. 1;

FIG. 8 is a fragmentary view in section of another arrangement of across-over assembly in the system of FIG. 1;

FIG. 9 is a fragmentary view in section of another arrangement of across-over assembly of the system of FIG. 1-

i FIG. 10 is a fragmentary view in section of another arrangement of across-over assembly of the system of FIG. l;

FIG. 11 is a still further arrangement including a sliding sleeve valveof a cross-over assembly in the system of FIG. 1;

FIG. 12 is a fragmentary view in section of another arrangement of across-over assembly including a sleeve valve in the system of FIG. 1;

FIG. 13 is a fragmentary view in section of another arrangement of across-over assembly including a sleeve valve in the system of FIG. 1;and

FIG. 14 is a fragmentary view in section of a still further arrangementof a cross-over assembly including a sliding sleeve valve in the systemof FIG. 1.

Referring to FIG. l of the drawings, a well system 20 embodying theinvention is particularly adapted to production by gas lift procedures,may be connected with an offshore location, and is well suited to theremote installation and removal of gas lift valves by pumping methods.The well system includes a well 21 having a casing 21a which may extenddownwardly through and be perforated at a producing formation, notshown, and is closed at its upper end by a well head 22. A pair ofspaced parallel tubing strings 23 and 24 are supported in sealedrelationship through the well head, the tubing string 23 extendingdownwardly through a suitable well packer 25 which seals around thetubing string within the casing above the producing formation. Above thepacker the tubing string 24 is connected with the tubing string 23 by aconduit 30'. The tubing strings communicate with each other at selectedspaced depths within the well through la plurality of spaced H-shapedcross-over assemblies 32. The particular form of cross-over assemblyshown schematically in FIG. l and illustrated in enlarged detail inFIGS. 2 and 2A has landing nipple recesses 33 and 34 and a slidingsleeve valve 35 which controls communication through a horizontal owpassage 40 connecting spaced vertical flow passages 41 and 42 whichcommunicate with and form portions of the tubing strings 23 and 24,respectively. Each of the cross-over assemblies provides communicationbetween the tubing strings at spaced locations along the lengths of thestrings and also support gas lift valves and other desired well toolswithin the tubing strings. A collar stop 31 is secured in the tubingstring 23 above the conduit 30 for use with pump-down tools as discussedin detail hereinafter.

The tubing strings 23 and 24 extend from the well head 22 to a remotelylocated shore installation 43 at which various control functions foroperating the well system are carried out. The tubing string 23 isconnected through spaced valves 44 and 45 defining a lubricator tubingsection 50 for the loading and unloading pumpable well tools. Similarly,the tubing string 24 includes valves 51 and 52 spaced to define alubricator tubing section 53 in the tubing string 24 at the shoreinstallation. The lubricator sections 50 and 53 communicate through aconduit 54 which connects into the lubricator sections near the valves45 and S2, respectively, so that liquid may be pumped into -thelubricators for displacing well tools from the lubricators through thetubing strings into the well. The conduit 54 is connected through a pairof spaced valves 55 and 60 between which a conduit 61 is connected intothe conduit 54. The conduit 61 leads to a reservoir tank 62 through apump 63 and includes valves 64 and 65 spaced on opposite sides of theconduit 54. A return line 70 including a valve 71 is connected from thetank 62 into the conduit 54 between the valve 60 and the connection ofthe conduit 54 into the lubricator section 53 of the tubing string 24.Similarly, a line 72 including a valve 73 is connected from the tank 62into the conduit 54 between the valve 55 and the lubricator section 50of the tubing string 23. The installation 43 provides facilities forpumping well tools such as gas lift valves to and from the landingnipples in the tubing strings and for directing lift gas into the wellthrough one of the tubing strings while recovering well fluids from thewell through the other of the tubing strings. During both the gas liftprocedures and the steps of installing and removing well tools thecasing annulus 26 within the casing 21a around the tubing strin gs mayremain liquid full.

The preferred connections between the tubing strings 23 and 24 withinthe Well comprise the H-shaped cross-over member 32 shown in detail inFIGS. 2 and 2A. The cross-over assembly includes a central cylindricalbody provided with spaced parallel vertical bores defining the flowpassages 41 and 42 which communicate through the horizontal flow passage40. The passage `40 is defined by a horizontal bore drilled in the body80 from the outside of the body through the pasage 41 with the openingformed in the outside wall of the body opening into passage 41 beingclosed by a plug 81 welded to the body 80 at 82. Flow between thevertical flow passages 41 and 42 in the body through the flow passage 40is controlled by a sliding sleeve valve 83 which is slightly reduced inexternal diameter along a central portion 84 provided with a pluralityof circumferentially spaced slots 85. Upper seal rings and lower sealrings 91 are disposed in internal annular recesses within the body 80above and below the bore 40 for sealing around the sleeve valve 83 sothat when the valve is moved from the position shown in FIG. 8downwardly to its lower end position fluid flow may not occur from thepassage 40 into the sleeve 83. The sleeve 83 has an internal annularboss 92 for engagement of a sleeve shifting tool, not shown, for movingthe sleeve valve between its upper open position and lower closedpositions. The sleeve valve is releasably locked at its upper openposition by a snap ring 93 disposed in an internal annular recess 94 inthe body 80 around the bore 41 and received in an external lockingrecess 95 defined along the lower end portion of the sleeve 83. An upperexternal locking recess of the sleeve 83 below the internal boss 92receives the snap ring 93 when the valve sleeve is at its lower closedposition for locking the valve at such position.

An upper tubing string section 23a is threaded into the upper endportion of the bore 41 of the body 80 with the upper end surface of thevalve sleeve 83 being engageable with the lower end surface of thetubing section 23a to limit the upward travel of the sleeve valve at theposition illustrated in FIGS. 2 and 2A. An O-ring seal 101 is disposedbetween the lower end portion of the tubing section 23a and the surfacedefining the bore 41 in the body to prevent leakage from the bore 41outwardly along the connection between the body and the tubing section23a. An upwardly extending section of the tubing string 23 is threadedinto the upper end of the tubing section 23a,

FIG. 2. Similarly, an upper tubing section 24a is threaded along a lowerend portion into the upper end of the bore 42 of the body and welded tothe body at 102 to prevent leakage between the body and the tubingsection. The locking recesses 33 and 34 as illustrated in FIG. 2 areformed within the upper tubing sections 23a and 24a respectively toprovide for locking well tools such as .gas lift valves in each side ofthe cross-over assembly as desired or required by the particularprocedure to be carried out by the well system. Upwardly extending toportions of the tubing string 24 and connected by a coupling 103 to theupper end of the tubing section 24a.

A lower tubing section 23b is threaded into the lower end of the bore 41of the body 80` with the upper end surface of the tubing section 23bsupporting the snap ring 93 in its recess 94. An O-ring seal 104 isdisposed in a recess of the body around the tubing section 23b and sealsbetween the tubing section and the body at the connection of the tubingsection into the body. An internal shoulder 23C limits downward travelof the sleeve valve which telescopes along its lower end portion 83ainto the upper bore portion 23d of the section 23b when the sleeve valveis closed.

Downwardly extending portions of the tubing string 23 are connected tothe lower tubing section 23b by a coupling 105. A lower tubing section2411 is threaded into the lower end of the bore 42 of the body 80 weldedat 110 sealing between the body and the tubing section 24h. Downwardlyextending sections of the tubing string 24, not shown in FIG. 2A, arecoupled with the tubing section 24b by a coupling 111.

It will be evident in making up the pair of inter-connected tubingstrings 23 and 24 coupled by the cross-over assemblies 32 that after thecross-over assemblies are connected in one of the tubing strings theconduits comprising the other tubing string cannot be manipulated in thenormal manner of a single tubing string thereby requiring specialconduit couplings. For example, when running the tubing strings into thewell, if the cross-over assemblies are made up in the tubing string 24,the assemblies along with the inter-connecting pipe sections of thetubing string 24 may be screwed together or assembled in the same manneras a single tubing string. However, it will be evident that after thecross-over assemblies are connected in the string 24 the assembliescannot be rotated to make up the tool string 23. Thus, special couplingapparatus is needed in making-up the pair of tubing strings forconnecting the second of the strings to be connected. This function isserved by a travel-limiting swivel joint '120 shown in FIG. 4. Theswivel joint includes an upper internally threaded coupling 121 securedby lower internal threads 122 on an uper externally threaded end portion123 of an inner tubular mandrel 124. The coupling 121 has an upper setof internal threads 125 which have the same pitch as external threads130 formed along a major lower portion of the inner mandrel 124. Thethreads 130 engage internal upper threads 131 formed within an outermandrel 32 threaded along a lower end portion 133 on an upper externallythreaded portion 134 of a lower coupling or bottom sub 135. Below itsthreads 131 the mandrel 132 has a smooth internal bore surface 140 whichextends substantially the full distance between the upper internalthreads 131 and the lower internally threaded end portion 133. O-rings1-41 and 142 disposed in external annular recesses along the lower endportion of the mandrel 124 seal around the mandrel with the bore surface140` at any position of the mandrel 124 within the mandrel 132 so longas the seal rings are below the shoulder 14011. An O-ring 143 isdisposed in an external annular recess around the upper end portion ofthe coupling 135 above its upper external threaded section to sealaround the coupling within the mandrel 132. The lower end portion of thecoupling 135 has threads 144 for connection of the lower end of theswivel joint with a tubing string section.

The travel-limiting swivel joint provides a conduit 75 coupling or jointwhich is adjustable in length over a distance equal to approximately thelength of the smooth bore surface 140 of the mandrel 132. The swiveljoint as shown in FIG. 4 is adjusted to its minimum length at which themandrel 124 is telescoped into the mandrel 132 until the lower end ofthe mandrel is adjacent to the upper end ot' the lower coupling 135. Theswivel joint is extended to its maximum length or any intermediatelength by rotation of the mandrel 124 to unthread it from the lowermandrel 132. The mandrel 124 obviously cannot be unthreaded beyond theextended position at which the O-rings 141 and 142 are below theshoulder 140a in the bore of the lower mandrel. The direction of thethreads on the inner mandrel upper end portion 123 is opposite to thedirection of the threads in the coupling 121 and 130 on the mandrel 124.For example, if the threads on the end portion 123 are left-handthreads, the threads must be right-hand threads so that the coupling 121may berotated counterclockwise tending to tighten the coupling on themandrel 124 while the mandrel 124 is being unthreaded out of the lowerouter mandrel 132. With the threads 125 also right-hand threads theupper portion of the upper coupling 121 may be threaded on a tubingsection above it, for example, to the lower threaded end portion of thesection 231; of the cross-over assembly 32 as the coupling 121 tightenson the mandrel 124 and the mandrel 124 is unthreaded or extendedupwardly in the mandrel 132.

The swivel joint 120 is particularly adapted to the preferredarrangement of tubing strings illustrated in FIG. l where a plurality ofthe cross-over assemblies 32 are included in and couple the tubingstrings together in the well. In making up and lowering the paralleltubing strings in the well, one of the strings is made up in aconventional manner with the sections of pipe comprising the stringbeing connected together as the strings are lowered into the well. Theportion of the tubing string 23 below and extending through the packer25 is made up by standard procedures and the packer and strings arelowered into the Well with the string 23 and the lower end of the string24 being connected by the horizontal coupling or connector 30. Thetubing sections comprising each of the strings 23 and 24 are connectedtogether in a conventional manner as the parallel strings are loweredinto the well bore until the lowermost cross-over assembly 32 isconnected into the strings. In connecting the cross-over assembly intothe tubing strings, the assembly may be rst coupled by means of thecoupling 111, FIG. 2A, to the upper end of a section of pipe in thetubing string 24 with the cross-over assembly being tightened in thetubing string until its section 23a1 is aligned with the pipe sectionscomprising the string 23 below the cross-over assembly. Since thecross-over assembly cannot be rotated to tighten it on both the tubingstring 23 and 24, sufficient pipe sections are connected into the tubingstring 23 to extend the tubing string upwardly toward the cross-overassembly 32 until the upper end of the tubing string is spaced below thecrossover assembly a distance slightly greater than the minimum lengthof the swivel joint 120. The travel-limiting swivel joint 120 is thenconnected by its lower threaded portion 144 into a coupling, not shown,on the upper end of the uppermost pipe section comprising the tubingstring 23 below the cross-over assembly. When the lower end portion 144on the swivel joint is screwed into the coupling at the end of theuppermost pipe section forming the tubing string 23, the coupling 121 atthe upper end of the swivel joint is spaced a short distance below thelower threaded end portion of the section 23b of the cross-overassembly. The swivel joint is then extended by turning the coupling 121to screw the threads 125 of the coupling on the lower threaded endportion of the section 23b of the cross-over assembly. As the coupling121 is rotated to screw it on to the section 2319, the oppositedirection of the threads on the mandrel upper end portion 123 tends totighten the coupling on the mandrel and thus unscrew the mandrel 124from the lower outer mandrel 132 because of the relation of the threads130 and the threads 131. The mandrel is telescoped or extended upwardlyrelative to the mandrel 132 until the coupling 121 is tightly connectedon the crossover assembly section 23b.

The identical characteristics of the threads 125 and the threads 130 and131 effect the exact corresponding movement of the coupling 121 onto thecross-over assembly and of the mandrel 124 relative to the mandrel 132.The seals 141 and 142 maintains a sealed relationship between themandrel 124 and the mandrel 132 along the smooth inner bore surface 140of the mandrel 132 as the mandrel 124 is telescoped upwardly in themandrel 132 to cornplete the connection of the swivel joint in thetubing string 23. Thus, the travel-limiting joint permits the connectionof pipe sections within the tubing strings between the cross-overassemblies. A travel-limiting swivel joint must be used in one of thetubing strings between each pair of cross-over assemblies in order to beable to connect the parallel tubing strings together and run them intothe well. Other than in the use of the travel-limiting swivel joints,the various pipe sections, couplings, and other related equipment of thewell system 20 and the installation 43 are conventional in structure andinstallation.

The well system 21 is useful with a variety of types of gas lift valveswhich may be landed and locked in either of the tubing strings at thecross-over assemblies depending upon the characteristics of theparticular valve employed. In one preferred arrangement of the wellsystem the tubing string 23 serves as the production string, the tubingstring 24 functions as the gas injection string, and the gas lift valveillustrated in FIG. is used at the cross-over assemblies to provide asystem in which the gas lift valves are disposed in the lift gasinjection path isolated to a maximum extent from the well fluids in theproduction string.

The gas lift valve 150 is landed and locked in each of the cross-overassemblies at which gas lift transfer may be desired from the tubingstring used for gas injection through the cross-over assembly into theproduction tubing string. The gas lift valve has a tubular body 151provided with a full bore opening 152 throughout its length for flow ofinjection gas through the valve and to allow other well tools to passthrough the valve. The body has a plurality of circumferentiallyextending longitudinal-v ly spaced central slots 153 for exit of liftgas from the bore 152 outwardly from the body. Flow of gas from the borethrough the slots 153 is controlled by a flexible tubular valve member154 clamped along a lower thickened end portion 155 between the body anda lower tubular housing 160 secured on the body and defining an annulardome gas chamber 161 between the body and the housing. The housing 160has an upper reduced portion 162 which telescopes into an upper tubularhousing 163 secured in spaced relation around the body 151. The valve154 is disposed in an annular space 164 between the mandrel and thehousing 160. A thickened upper end portion 165 of the Valve 154 isclamped against the inner wall of the upper housing member 163 by anannular retainer 170 secured by lock ring 171 along an enlargedlongitudinally slotted portion 172 of the body 151. The lock ring 171 isdisposed within a flange portion 173 of the retainer below which theretainer has an external annular recess 174 which receives the thickenedportion 165 of the valve 154. The lower thickened portion 155 of thevalve is clamped in annular recess 156 around the body by the portion162 of the housing 160. The portion 172 of the mandrel 151 includesvertically extending circumferentially spaced slots 175 for directinglift gas from the valve 154 along the body.

A flexible tubular check valve 180 is clamped along a lower end portion181 between the housing 163 and the retainer 170 above its flange 173.The check valve 180 has a free upper skirt portion 182 which is movablebetween a contracted relaxed position as shown in FIG. 5 to an expandedflared position, not shown, which allows upward flow past the checkvalve. At the contracted collapsed position shown the valve skirt liesagainst the upper tapered end surface of the enlarged slotted bodyportion 172 over the upper ends of the slots 175 to prevent back flow offluids into the gas lift valve. One or more ports 183 open upwardly andoutwardly through a shoulder 163a of the housing 163 for exit of thelift gas from the valve.

The annular space 161 between the housing 163 and the body 151 forms adome gas chamber for dome gas to bias the central free portion 154a ofthe valve 154 toward the closed position over the slots 153 in the body.A fitting 190 in the housing 160 provides for injection of dome gas intothe annular space 161. A small horizontal passage 191 communicates thereduced upper end portion of the dome gas chamber 161 with alongitudinal slot 192 along the reduced upper end portion 162 of thehousing for flow of dome gas from the chamber 161 upwardly into theannular space 164 around the valve 154.

An O-ring seal 193 disposed in an external annular recess at the lowerend of the upper reduced end portion 162 of the housing 160 sealsbetween the housing 160 and the internal surface of the lower portion ofthe upper housing 163. Similarly, an O-ring seal 194 is disposed in anexternal, annular recess around the body 151 sealing between the bodyand the lower end portion of the housing 160. The housing 160 isretained on the mandrel by a lock ring 195 disposed in alinged recessesin the body 151 and the housing 160 to lock the housing on the mandrel.The lock ring is inserted through a conventional slot, not shown,opening through the housing at the lock ring recess within the housing.

The upper, outer housing 163 has an enlarged portion 200 above the ports183 through which a plurality of set screws 201 are threaded intoaligned recesses on the body 151 to hold the housing 163 in position onthe mandrel. An O-ring seal 202 disposed in an external, annular recessin the body seals between the body and the upper housing 163 below theset screws 201.

When the pressure of the dome gas exceeds the pressure of lift gaswithin the body bore 152 at the slots 153, the central portion 154a ofthe valve 154 is pressed over the slots 153 preventing outward flow oflift gas from the the gas lift valve body 151. An O-ring 221 sealswithin the bore 152 at the slots 153 exceeds the dome gas pressure thecentral portion of the valve 154 is expanded outwardly releasing liftgas to flow outwardly through the slots 153 and upwardly along the slots175 around the mandrel within the retainer 170. The lift gas flowsupwardy from slots past the check valve 182 exiting from the gas liftvalve through the ports 183.

Upper and lower seal assemblies 205 and 210, respectively, are pivotallysecured on the gas lift valve for sealing above and below the valvewithin a flow conductor such as the flow strings 23 or 24 above andbelow the exit ports 183 so that the lift gas is discharged from thevalve into an annular space defined within the flow conductor betweenthe seals of the upper and lower seal assemblies. The upper sealassembly comprises a mandrel 211 having an upper threaded end portion212 and supporting an annular seal 213 for sealing around the assemblywithin a flow conductor. A bore 211a of the mandrel communicates withthe bore 152 of the gas lift valve. An annular ball member 214 having aspherical outer surface 215 is threaded on the upper end portion 220 ofthe gas lift valve body 151. An O-ring 21 seals within the ball member214 around the body. A socket retainer 222 having an internal sphericalsurface 223 engaging the ball member 214 is threaded on the lower endportion of the mandrel 211 to pivotally retain the seal assembly on theupper end of the gas lift valve. An O-ring 224 seals within the capretainer with the ball member 214 to prevent leakage along the balljoint. Another O-ring 225 seals between the cap member 222 and themandrel 211. A nylon ball 230 locks the cap member 222 on the mandrel211. The ball 230 is installed after tirst adjusting the cap member onthe mandrel to the proper position. A horizontal hole 231 is thendrilled through the upper end portion of the cap and into the mandrel atthe boundary between the cap and the mandrel. The lower half of the holeis drilled in the cap 222 and the upper half of the hole in the mandrel211. The nylon ball 230 is then tightly pressed into the hole to preventthe loosening of the screw connection between the cap 222 and themandrel 211.

The lower seal assembly 210, pivotally connected on the lower endportion 240 of the mandrel 151, is identical in structure and assemblyto the upper seal assembly 205 with the various parts of the lower sealassembly being referred to by the same reference numerals as those usedin connection with the upper seal assembly and further identied with thesubscript a. The structure of the lower seal assembly thus is notfurther described in detail in view of the above description of theupper seal assembly.

Each gas lift valve is locked in its cross-over assembly 32 by asuitable locking unit which may be one of a number of available lockingunits depending upon the particular technique to be employed ininstalling and retrieving the gas lift valves. The well system and thesurface installation 43 may be located and arranged so that wirelineequipment and techniques may be used for installing and retrieving gaslift valves with commercially available locking mandrels. A suitablelocking mandrel for wireline use is the Type X Otis Locking Mandrelillustrated at page 3766 of the 1968-69 Composite Catalog of Oil FieldEquipment and Services, published by World Oil, Houston, Tex. In usingthe Type X Mandrel, the upper packing assembly 20S of the gas lift valve150 is connected with the lower end of the locking mandrel by a suitablethreaded coupling, not shown. The locking dogs of the mandrel arereceived in either the locking recess 33 of the tubing string 23 or thelocking recess 34 of the tubing string 24. Obviously, the longitudinaldimensions and spacing of the various components of the locking mandreland the gas lift valve are proportioned to position the gas lift valvein alignment with the cross-over assembly flow passage 40 therebylocating the upper and lower seal assemblies 205 and 210, respectively,above and below the cross-over ilow passage so that lift gas injectedthrough the valve travels through the passage 40 between the tubingstring 24 side of the cross-over assembly and the production tubingstring 23 side of the assembly.

If the gas lift valve 150 supported by a suitable locking mandrel isused in the preferred arrangement of the well system 21, with the tubingstring 23 serving as the production string and string 24 as the gas liftinjection string, a gas lift valve may be locked in the productionstring 24 at each cross-over assembly 32. The lowest gas lift valve tobe installed in the string 24 is run, landed, and locked irst with eachsubsequent valve up the string being individually installed until thelast and top valve has been placed in its cross-over assembly. Ofcourse, a complete round trip into and out of the tubing string isnecessary for the wireline installation of each of the valves at, leastwith presently available equipment and techniques. It will be apparentthat the proiiles of the locking recesses, such as the locking recess 34in the upper section 24a of the cross-over assembly, are designedcompatible with the profile of the locking dogs on the locking mandrelso that the dogs are received in the locking recess for properlysecuring the gas lift valve by means of the mandrel at the desiredposition within the tubing string at the cross-over assembly. It is awell known expedient to provide a slightly different locking recessprole at each cross-over assembly with corresponding proles on thelocking mandrels of the gas lift valves so that each Valve is lockableat only the cross-over assembly which has a locking recess correspondingwith the locking dogs on the mandrel supporting the gas lift valve.

It will be evident that the sliding sleeve valve 35 in each cross-overassembly must be either open or closed depending upon whether or not agas lift valve is in the other side of the cross-over assembly, and, ifpresent, whether the valve is to be functional in gas lift procedures inthe well system. Using wireline procedures for installation of the gaslift valves eliminates the need for a pre-adjustment of the slidingsleeves before valve installation, though they must be open or closedprior to gas lift injection, depending upon which valves are tofunction. At each cross-over assembly the sleeve 35 is open after a gaslift valve has been landed and locked in the cross-over assembly and gasis to be admitted through the valve to the production string. If the gaslift valve is present but is not to be presently used for gas liftadmission, the sleeve valve in the cross-over assembly holding the gaslift valve may be closed. Where a gas lift valve is not required in aparticular cross-over assembly the sleeve valve is closed to preventby-pass of lift gas directly from the injection string 24 into theproduction string 23. Where the gas lift valves are installed andretrieved by wireline methods, the sleeve valves in the cross-overassemblies likewise may be manipulated by wireline apparatus andprocedures. For example, at page 3774 of the Composite Catalog of OilField Equipment and Services, supra, a type B Otis Positioning Tool isillustrated which may be used to shift the sleeves 83 between their openand closed positions. Obviously, the prole of the shifting keys of thepositioning tool must conform to the internal prole of the sleeve sothat the tool keys may engage and properly release from the sleeve forraising and lowering the sleeve in the cross-over assembly.

Another technique and system which may be adapted to installing andremoving the gas lift valves in the cross-over assemblies of the wellsystem 21 are illustrated and described in United States Patent3,334,690 issued to H. U. Garrett, Aug. 8, 1967. The use of the Garrettsystem and apparatus is one of several available approaches to theinstallation of gas lift valves by pump-down procedures when wirelinetechniques are not practical or particularly desired and especially inolfshore installations as where the installation 43 is removed fromabove the well system 21. As previously noted, the installation 43 maybe at a shore location while the well system 21 is horizontally removedat a subsea location with its well head 22 at or near the ocean bedsurface. FIG. 6 illustrates the Garrett apparatus adapted to gas liftvalves 150 so that a plurality of the gas lift valves may be installedin the tubing string 24 in a single operation including one run of thetool string containing the gas lift valves.

Referring to FIG. 6, each gas lift valve 150 is adapted to the Garrettapparatus by tting it with a locking dog assembly 330 threaded on thelower end of the seal assembly 210 and a fishing head 332 threaded onthe upper end of the seal assembly 205. The dog assembly includes a pairof radially expandable and contractable dogs 33741 disposed within atubular housing 330b threaded on the the lower end of the lower sealassembly 210. The dogs 337a are biased outwardly by a spring 344 andthey expand and contract through windows 330e in the housing 330b. Theouter profiles of the dogs are receivable in a locking recess 329provided in a modiiied form of the cross-over assembly 32 below thehorizontal flow passage 40 on the tubing string 24 side of the assemblyfor locking the gas lift valve at an operating location in eachcrossover assembly. The inner edge surfaces of the locking dogs haveprofiles which are shaped to secure the dog assembly on the fishing headof a gas lift valve in the tool train immediately below. The lishinghead is inserted into the dogs when they are expanded as shown in FIG.6. When the tool train is inserted into the tubing string the wall ofthe tubing holds the dogs inwardly locking the shing head in the dogassembly until a recess 329 is reached when one gas lift valve locks atthe recess and the fishing head of the next valve is released to allowthe tool train to continue. A complete tool train of the gas lift valves150 with the Garrett apparatus includes the Garrett piston 76 forpowering or pumping the tool train through the tubing string. Theiishing head body 332a has a plurality of ports 332b to permit fluid lowthrough the shing head and the gas lift valve as the gas lift valve ispushed through a tubing string. As the tool train is pumped in thetubing string the dogs 337a are held inwardly by the wall of the tubinguntil they arrive at a locking recess 329 which permits the dogs toexpand with their outer profiles being received within the lockingrecess to lock the gas lift valve in the tubing at the cross-overassembly so that the valve itself and its upper and lower sealassemblies are properly positioned to direct lift gas through thehorizontal ow passage 40 of the cross-over assembly. When the valve dogsexpand to lock it at a recess 329', the fishing head of the valveimmediately there-below is released lby the expansion of the dogs sothat the lower valve may continue its downward movement until it arrivesat the next locking recess for release and locking at the nextcross-over assembly. The profile of the locking dogs and the lockingrecesses 329 are correlated so that the uppermost valve is released andlocked in the uppermost cross-over assembly with the valves then beingsequentially released and locked as the tool train moves down the tubingstring.

The tool train comprising the plurality of gas lift valves with theGarrett power piston 76 is introduced into the installation 43 at thelubricator section 53 for pumping into the tubing string 24. With thevalve 51 closed and the valve 52 open, the tool string is introducedinto the open end of the lubricator section of the tubing string. Whenthe string is fully in the lubricator section the valve 52 is closed,the valve 51 is opened, and fluid circulation through the well system 21is established. The tool train is pumped into the tubing string by aliquid such as water or oil from the reservoir tank 62, the liquidhaving been previously introduced into the tank through open valves 64and 65 and the pump 63. The valves 71, 55, and 65 are closed, and thevalves 60 and 64 are opened so that the pump 63 draws liquid from thetank 62 discharging it through the open valve 64 and the valve 60 in theconduit 54 into the outward end of the lubricator portion 53 displacingthe tool train through the open valve 51 into the tubing string 24.Liquid in the tubing string 24 is displaced at the lower end of thestring across through the member 30 into the lower end of the tubingstring 23 and upwardly through the tubing string back toward the surfaceinstallation 43. The valves 45 and 55 are closed and the valves -44 and73 are open so that liquid in the tubing string 23 is returned throughthe lubricator section 50 and the portion of the conduit 54 between thevalve l55 and the lubricator section and the conduit 72 back to thereservoir tank 62. Thus, a complete closed fluid circulation path isestablished from the tank 62 through the tubing string 24 with returnsthrough the tubing string 23 to the tank.

The tool string is displaced downwardly in tubing string 24 with theseveral gas lift valves in the tool string being released and locked atthe cross-over assemblies in accordance with the teachings of theGarrett patent which may be referred to for further details of themanner of operation of the Garrett pump-down system. The sleeve valves35 in each of the cross-over assemblies may be open or closed duringpumping of the tool string downwardly in the tubing string 24. If thesleeve valves are open as the tool train passes each of the cross-overassemblies and releases and locks a gas lift valve, the passage 40 isclosed by the valve, and if the diplacing liquid pressure is below theopening pressure for the gas lift valve no bypassing occurs. lf desiredthe sleeve valves may be lirst closed by any suitable means andsubsequent to the setting of the gas lift valves the sleeve valves arereopened. Leaving the 12 sleeve valve open during the setting procedurewould reduce the round trips into the well, however.

With the gas lift valves locked in the cross-over assemblies and thesliding sleeve valves open, the tool pumping equipment of the system isisolated from the remainder of the well system at the surfaceinstallation 43 by closure of the valves 60, 71, 55, and 73 preparatoryto initiation of gas lift procedures in the well system. With the gaslift valves supported as indicated in the tubing string 24, lift gasfrom a suitable source, not shown, is forced through the tubing string24 downwardly through the gas lift valves. In accordance with knownprocedures and prior to the installation of the gas lift valves, thepressure the valves should be adjusted to open is determined and thedome gas pressure in the chamber 161 of each valve is established at avalue which will provide for the opening of the valve 154 at suchpressure. Generally, it is preferred that the uppermost valves such asthe first and second valves highest in the well initially function withthe lower valves being available for future use if and when the liquidlevel in the well is lowered. The lift gas is forced downwardly in thetubing string 24 into the central bores 152 through the gas lift valvesand when the pressure of the lift gas is suicient to overcome the domegas pressure in the chamber portion 164 around the valve 154, thecentral portion of the valve is expanded outwardly uncovering the slots153 allowing the lift gas to ow upwardly through the slots 175 past thecheck valve 182 exiting from the valve through the ports 183 into thecross-over assembly bore -42 between the upper and lower lift valve sealassembly 205 and 210. The gas flows laterally through the horizontalflow passage 40 in the cross-over assembly and the ports in the opensleeve valve 83 entering the production tubing bore of the sleeve valvedisplacing well liquids upwardly in the production tubing string 23 andfrom the well through the tubing string to the surface installation 43.The well uids are produced through the tubing string 23 to liquidstorage and treatment facilities, such as separators and the like, notshown, downstream from the valve 45. The tubing strings 24 and 23communicating through the cross-over assemblies thus define a closedcircuit iiow path or paths within the well for the gas injection andwell iiuids recovery which are isolated from surrounding spaces in thewell such as the annulus 26 within the well casing around the tubingstrings. The annulus 26 may thus be maintained liquid filled and ifdesired, could be filled with cement surrounding the tubing strings. Itwill be recognized that if it should be desired that the tubing stringsbe cemented in the well, the well casing 21a could be dispensed with.

Other available gas lift valves may be installed in the well system 21either by wireline procedures or pumpdown procedures depending upon thearrangement of the well system with the installation 43 and the types ofgas lift valves to be used. For example, the Otis Type C Gas Lift Valvemay be installed in the production tubing string where the other of thestrings is to be used for lift gas injection. At page 3850` of theComposite Catalog of Oil Field Equipment and Services, supra, the Type CGas Lift Valve is illustrated in use in a mandrel having a slidingsleeve valve of the nature of the valve 35 represented diagrammaticallyin FIG. 1. With the Otis Type C Gas Lift Valve installed in each of thecrossover assemblies 32 of the well system 21, the lift gas is injectedin the tubing string 24 from which it ilows through the passage 40 ineach cross-over assembly into the tubing string 23 around the gas liftvalve between its upper and lower packing sections. The gas flowsinwardly through the gas lift valve in the manner illustrated in thereference with well iiuids being produced by the lift gas through thetubing string 23.

Another type gas lift valve which may be utilized in the producingstring of the system 21 with gas injection being effected in the otherof the parallel interconnected strings is illustrated and described inUnited States Patent 13 3,375,847 issued to Norman F. Brown, Apr. 2,1968. `The Brown gas lift valve is lflexible and thus readily traversescurves in a tubing string making it especially desirable for offshoreoperations where it is delivered and retrieved from a land basedinstallation through tubing strings having curved portions such as thetubing strings 23 and 24. As pointed out in the Brown patent, the valvemay be installed by either wireline procedures or pump-down proceduresas explained therein. Obviously, for the well sysstem 21 to receive theBrown gas lift valves the crossover assemblies 32 must be provided withlocking recesses having proper profiles and properly positioned toaccept the locking dogs and selector keys shown in FIG. 2 of the Brownpatent. In positioning the Brown gas lift valve in the well system, itwill also `be noted that the locking assembly of the Brown patent withits upper seal assembly 71 is located above the cross-over passage 40 ofthe crossover assembly while the lower packing 184 of the Brown valve islocated below the cross-over passage so that lift gas entering from theparallel tubing string will be directed between the upper and lowerpacking to the admitting ports 153 of the Brown valve. With theparticular equipment illustrated in the Brown patent such valves areinstalled and retrieved individually thus requiring a complete roundtrip for each valve in the system.

When the gas lift valves used in the well system 21 are of the typewhich are installed and retrieved by pumpi down procedures, it isparticularly desirable that the sleeve valves of the cross-overassemblies be movable between their open and closed positions bypump-down sleeve shifting apparatus. One such set of tools isillustrated and described in a United States patent application Ser. No.709,652, entitled Well Tools, filed by Harry E. Sch-wegman-on the irstday of March 1968. The Schwegman sleeve shifting tools are adapted toshift the sleeve valves in either an upward or a downward direction andmay be assembled in a single tool train for down-shifting during adownward trip of the train and up-shifting during the return or upwardtrip of the tool train. Under some circumstances the sleeve shiftingtools are included in a tool train with gas lift valves and their latchassemblies for shifting the sleeve valves downwardly closed during thedownward trip of the tool train and moving them back upwardly open asthe tool train returns to the surface dropping off or releasing andlocking a gas lift Valve at each cross-over assembly.

Another system of gas lift valves and related equipment for theinstallation and retrieval of the valves along with the 'shifting ofsleeves at the landing nipples supporting the valves in the tubingstrings are illustrated and described in U.S. Pats. 3,419,074 and3,419,075, both entitled Well Tools issued on Dec. 31, 1968, to NormanF. Brown. The valves and other equipment described and claimed in theBrown patents may be used in the production string of the present system21 with lift gas injecjection in the parallel tubing string and the liftgas llowing across into the production string through the crossoverassemblies as previously explained. Those forms of theV gas lift systemof the present invention using the Brown valves and installation andretrieval equipment and techniques are operated during the gas liftphases as previously described.

The several gas lift valves and the equipment and techniques forinstallation and retrieval of such valves already described in terms oftheir use in the particular arrangement of the well system 21 shown inFIG. 1 are also applicable to the variations of the well system represented in FIGS. 7 through 14. The variations shown in FIGS. 7 through 14represents diiferent forms of only the cross-over assemblies of the wellsystem and the location of the gas lift valve.

It will be apparent that FIGS. l1 and 14 correspond with the system 21as shown in FIG. 1. FIG. 11 sc'hematically shows a gas lift valve G andrelated supporting and sealing equipment M locked in the tubing string14 24 side of the cross-over assembly and the sleeve valve on the tubingstring 23 side. FIG. 14 shows the same cross-over assembly arrangementwith the gas lift valve, however, supported through the sleeve valve inthe tubing string 23 side.

FIG. 7 shows a cross-over assembly 32a having a locking recess 33a onthe tubing string 23 side of the assembly and a smooth bore on thetubing string 24 side of the assembly interconnected by the cross-overflow passage 40A. The gas lift valve G including its upper and lowerseal assemblies is shown supported from the locking mandrel M in thetubing string 23 side of the cross-over assembly. FIG. 8 shows across-over assembly 32b for use in the well system having a smooth boreon the tubing string 23 side of the assembly with a locking recess 34aon the tubing string 24 side of the assembly for the locking mandrel Msupporting the gas lift valve G.

The cross-over assembly 32e shown in FIGS. 9 and 10 includes a lockingrecess in the tubing string 23 side of the assembly and a locking recess34a` in the tubing string 24 side of the assembly. In the systemrepresented in FIG. 9 the gas lift valve G is supported in the tubingstring 24 side of the assembly while in FIG. 10 the gas lift valve issupported in the tubing string 23 side of the assembly.

While the embodiments represented in FIGS. 7 through 10 show diiferentgas lift valve locations and diiferent locking recess arrangements atthe cross-over assemblies, it will be particularly noted that no slidingsleeve valves are shown in any of the cross-over assembly arrangements.It will be apparent, therefore, that each gas lift system havingparallel tubing strings interconnected as shown in FIGS. 7 through 10will require a gas lift valve at each cross-over assembly forcontrolling communication between the tubing strings assembly, at leastat all depths at which the gas injection into the production string isexpected to take place. Below such depths there is no particularobjection to free communication between the tubings strings. It will beespecially noted that the tubing strings are in continuous communicationat their lower ends through the cross member 30 in all forms of the wellsystem represented herein.

Other arrangements of crosseover assemblies for use in the well systemare represented in FIGS. 11 through 14 all of which utilize a slidingsleeve valve, with FIGS. l1 and 14 showing the same cross-over assembly32 as represented in FIG. 1. In FIG. l1 the gas lift valve G issupported in the tubing string 24 side of the assembly while in FIG. 14it is supported through the sleeve valve in the tubing string 23 side ofthe assembly. In FIG. 12 the cross-over assembly form 32d has thelocking recess 33d on the tubing string 23 side with the sleeve valve35d and the locking recess 34d on the tubing string 24 side. The gaslift valve G is supported on the tubing string 23 side of the cross-overassembly. FIG. 13 shows the same cross-over assembly arrangement as inFIG. 12 with the gas lift valve, however, supported on the tubing string24 side of the assembly through the sliding sleeve valve. It will beapparent in the systems shown in FIGS. 11 through 14 that the slidingsleeve may be closed to prevent communication between the tubing stringsat those cross-over assemblies where a gas lift valve is not set orwhere it is desired that the gas lift valve not presently be functional.Obviously, where the gas lift valve is situated through the sleeve, thesleeve is not readily shiftable between open and closed positions solong as the gas lift valve is locked in place in the sleeve. Anotherrequirement for sliding sleeve valves in well systems of the naturedescribed herein is encountered where pump-down procedures are used forgas lift valve installation and retrieval. A sleeve valve is needed ateach cross-over assembly to properly direct displacing liquid forpumping the tool along the tubing strings. The sleeves must be closedbehind the tool train during installation and ahead of the train duringretrieval to prevent by-passing of the liquid between the tubing 15strings without pumping the tool train, as already explained.

In all of the variations of the cross-over assembly arrangement shown inlFIGS. 7 through 14, the type of gas lift valve used depends uponwhether the valve is located in the production or lift gas side of theassembly. If a gas lift valve of the nature of the valve 150 shown inFIG. is used, it is placed in the injection string side, while any ofthe other valves referred to herein as usable on the production side areplaced on the production string side and the rwell is produced throughthe gas lift valve.

It will be obvious that other arrangements of locking v recesses andsleeve valves at cross-over assemblies may be devised. The particularchoice of a cross-over assembly arrangement may depend on availableequipment, well conditions, and other considerations. Obviously, thoseforms using sliding sleeve valves and locking recesses on both sides ofthe cross-over assemblies offer more ilexibility in well systemarrangement. The form of crossover assemblies represented in FIGS. 7 and8 preclude the setting of a gas lift valve in the side of the assemblyhaving the smooth bore except by use of a form of locking mandrel havingslips adapted to engage the smooth bore wall creating, of course,problems in properly locating the gas lift valve at the cross-overassembly. However,

where it is intended to always locate the gas lift valves in oneparticular side of the well system, the forms shown in FIGS. 7 and 8should be quite satisfactory.

It has been stated that a particular advantage of the well system of theinvention is the reduction of the paraffin and sand problems,particularly in those forms of the well system Where the gas lift valvesare supported in the lift gas injection string and especially where thesliding sleeve valves are also located in the lift gas injection stringwith the gas lift valves supported through them as particularly shown inFIG. l13. While paraffin problems are encountered at relatively shallowdepths where the paraffin tends to solidify on the well tools andequipment, sand problems may be encountered at all depths where sand isentrained in the producing Well uids and thus tends to clog wellequipment. With the sleeve valves and gas lift valves in the lift gasinjection side of the well system, flowing particles of sand which mayfoul the sleeve valves and hinder their movement are largely limited tothe production string side of the system and thus the sleeve valves areprovided with maximum protection. Both the sand and paraflin are kept toa maxilmum extent away from both the sleeve valves and the gas liftvalves. The pressure of the lift gas in the injection string side of thesystem tends to depress the liquid level in the injection string withthe injection and tubing strings serving as a U-tube so that the liquidlevel remains substantially lower in the injection string than in theproduction string. The possibilities of sand getting to the gas liftvalves is very much minimized and generally only the upper-most valvesare within the paraflin range and they are generally -isolated from theliquid by virtue of the depression of the liquid level in the injectiongas side. Further advantages inherent in the well system having the gaslift valves in the injection string provide a full bore flow passagethroughout the length of the production string thereby substantiallyreducing the pressure drop in the production fluids as they ow upwardlyin the production string so that maximum production is obtained undergiven well conditions. This is to be distinguished from the normal gaslift system in which each gas lift valve in a production string providesa substantial restriction in the flow passage. Also, the unrestrictediiow passage provided throughout the length of the production stringpermits the pumping of a paraffin scraper or plug type well tool down.-wardly in the production string to displace paraffin deposits to a depthat which they readily melt and can be produced from the Well with thewell fluids. Over a period of time, paraffin deposits at the upperlevels in the production string often seriously obstruct liuid flow inthe 16 string. A still further advantage of supporting the gas liftvalves in the lift gas injection string rather than in the productionstring is that the valves can be retrieved without encountering parafiindeposits since the valves are inserted and withdrawn from the surfacethrough the tubing string functioning for lift gas injection.

From the foregoing description and the drawings., it will be seen thatthe present invention provides a well system particularly adapted toproduction by gas lift wherein lift gas is injected into a well throughone tubing string while well iiuids are produced in an adjacentinterconnected tubing string whereby the lift gas injection andproduction tubing strings *may be cemented in the well, oralternatively, if an annular space exists in the Well around the tubingstrings it may be maintained in a liquid filled condition. The inventionprovides maximum exibility in well equipment arrangement and gas liftvalve location within the broad concepts of separate tubing strings forgas lift injection and well uid production. lIn particular forms of thewell system described and illustrated, the gas lift valves are situatedin the tubing string used for lift gas injection thereby providingmaximum protection from sand and paraffin conditions to the gas liftvalves and also to such other equipment as sliding sleeve valves ifpresent in the lift gas side of the system. Further, a new and novel gaslift valve particularly adapted to use in the lift gas side of the wellsystem with lift gas being injected through a central ow passage in thegas lift valve has been described and illustrated. The gas lift systemis compatible with a number of available gas lift valves and equipmentand techniques for installation and retrieval of the lift valves.Cross-over assemblies for interconnection of parallel tubing strings ina well have been illustrated particularly for use in gas lift systemsembodying the invention. A novel travel-limiting swivel joint has beendescribed and illustrated for connecting tubing strings of a well systememploying parallel tubing strings which normally present problems inmaking up the second of the tubing strings to be connected and run. Thetravellimiting swivel joint enables connections to be completed betweenspaced cross-over assemblies which cannot be rotated during themaking-up of the tubing strings. The Well system accommodates eitherwireline or pump-down procedures for gas lift valve installation andremoval depending upon the particular arrangement of the Well and thesurface installation. Either tubing string in the system may be used forlift gas injection while the other string serves for the production ofwell fluids.

The foregoing description of the invention is explanatory only andchanges in the details of the construction illustrated may be made bythose skilled in the art within the scope of the appended claims withoutdeparting from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A well system comprising: means comprising a rst tubing stringdefining a first flow passage along a well; means comprising a secondtubing string defining a second flow passage along said well; said flowpassages being disposed in substantially parallel transversely spacedsideby-side relationship isolated from an annular space in said wellaround said ow passage; means connecting said first and second tubingstrings and providing a cross-over passage interconnecting said rst andsecond ow passages; each of said tubing strings being provided with alocking recess for a well tool locking mandrel for locking a well toolin either of said tubing strings at said cross-over passage; one of saidtubing strings being provided with a sliding sleeve valve at saidcross-over passage movable between open and closed positions forcontrolling communication between said tubing strings through saidcross-over passage; and a gas lift valve located in the tubing stringopposite the tubing string in which said sleeve valve is disposed forcontrolling communication between said rst and second flow passages 17through said crossover passage responsive to a predetermined fiuidpressure in at least one of said first and second flow passages.

2. A well system comprising: means comprising a first tubing stringdefinin-g a first ow passage along a well; means comprising a secondtubing string defining a second flow passage along said well; said fiowpassages being disposed in substantially parallel transversely spacedsideby-side relationship isolated from an annular space in said Wellaround said passages; means interconnecting said iirst and second tubingstrings providing a crossover passage within said well interconnectingsaid first and second liow passages; each of said tubing strings beingprovided with a locking recess for a well tool locking mandrel forlocking a well tool in either of said tubing strings at said cross-overpassage; each of said first and said second tubing strings beingprovided with a sliding sleeve valve movable between open and closedpositions for controlling communication between said tubing stringsthrough said cross-over passage; and valve means for controlingcommunication between said first and second passages through saidcross-over passage responsive to a predetermined fluid pressure in atleast one of said first and second iiow passages.

3. A well system comprising: means comprising a first tubing stringdefining a first flow passage along a well; means comprising a secondtubing string providing a second fiow passage along said well; said flowpassages being disposed in substantially parallel transversely spacedsideby-side relationship isolated from an annular space in said wellaround said flow passages; means interconnecting said tubing stringsdefining a cross-over passage within said well interconnecting saidfirst and second flow passages; each of said tubing strings beingprovided with a locking recess for a well tool locking mandrel forlocking a Well tool in either of said tubing strings at said crossoverpassage; a gas lift valve supported in the tubing string through whichlift gas is injected into said well system and well fluids are producedfrom said well in the other of said tubing strings by said lift gasadmitted through said cross-over passage to said other tubing string bysaid gas lift valve; said gas lift valve being provided with a centrallongitudinally extending passage substantially the diameter of the flowpassage along the tubing string in which said valve is disposed andextending the full length of the said valve for fiow of fluids includinglift gas through said gas lift valve and to permit movement of welltools through said gas lift valve, valve means providing for control ofoutward flow of lift gas from said central passage, and port means forexhaust of said lift gas outwardly from said valve to said cross-overpassage to said production string.

4. A well system for producing and servicing a well comprising: a firsttubing string supported in said well communicating with a producingformation intersected by said well, a second tubing string supported insaid well extending in side-by-side substantially parallel relationshipwith said first tubing string, said second tubing string being connectedinto said first string whereby one of said strings may provide an inputflow passage and the other of said strings 'a return flow passage forpumping well tools into and out of each of said tubing strings; one ofsaid tubing strings providing a flow passage for the recovery of wellfluids from said well; the other of said tubing strings providing a flowpassage for the injection of lift gas into said well; said fiow passagesin said tubing strings being isolated from an annular space around saidtubing strings within said well; a plurality of cross-over connectionsincluded in said tubing strings at spaced intervals along the length ofsaid strings, each cross-over connection providing a fiow passageinterconnecting said tubing strings for conducting lift gas from thetubing string into which lift gas is injected into said well into thetubing string through which well fluids are produced from said well.

5. A well system for producing and servicing a well comprising: a firsttubing string supported in said wel] communicating with a producingformation intersected by said well, a second tubing string supported insaid well extending in side-by-side substantially parallel relationshipwith said first tubing istring communicating along a lower portionthereof with said first tubing string, said second tubing string beingclosable at a location below connections provided between said tubingstrings whereby well tools are pumpable into and out of each of saidtubing strings by fiuid introduced into one of said tubing `strings atthe surface and returned to the surace through the other of said tubingstrings; one of said tubing strings providing a iiow passage for therecovery of well fluids from said well; the other of said tubing stringsproviding a iiow passage for the injection of lift gas into said well;said fiow passages in said tubing strings being isolated from an annularspace around said tubing strings within said well; a plurality ofcross-over connections included in said tubing strings at spacedintervals along the length of said strings, each cross-over connectionproviding a liow passage interconnecting said tubing strings forconducting lift gas from the tubing string into which lift gas isinjected into said Well into the tubing string through which well fluidsare produced from said Well.

i6. A well system as defined in claim 5 including a surface installationprovided with means for selectively pumping into either of said tubingstrings in said well while receiving iiuid returns from the other ofsaid tubing strings.

7. A well system as defined in claim 6 including means for inserting andwithdrawing well tool strings for pumping said well tool strings intoand out of either of said tubing strings in said well whereby well toolsare installed in and retrieved from said tubing strings from saidsurface installation.

8. A Well system for producing and servicing a well comprising: a firsttubing string supported in said well; a second tubing string supportedin said well extending in side-by-side substantially parallelrelationship with said first tubing string; one of said tubing stringsproviding a flow passage for the recovery of Well fluids from said well;the other of said tubing strings providing a tiow passage for theinjection of lift gas into said well; said flow passages in said tubingstrings being isolated from an annular space around said tubing stringsWithin said well; a plurality of cross-over connections included in saidtubing strings at spaced intervals along the length of said strings,each cross-over connection providing a flow passage interconnecting saidtubing strings for conducting lift gas from the tubing string into whichlift gas is injected into said well into the tubing string through whichwell fluids are produced from said well; and a lift gas valve installedwithin one of said tubing strings at selected ones of said cross-overconnections for controlling the fiow of lift gas between said strings,each said gas lift valve being installed by being pumped through saidinjection tubing string to and from an operating location at across-over connection within said string.

l9. A well system for producing and servicing a well comprising: a firsttubing string supported in said well; a second tubing string supportedin said well extending in side-by-side substantially parallelrelationship with said first tubing string; one of said tubing stringsproviding a fiow passage for the recovery of well fluids of said well;the other of said tubing strings providing a flow passage for theinjection of lift gas into said well; said flow passages in said tubingstrings being isolated from an annular space around said tubing stringswithin said well; a plurality of cross-over connections included in saidtubing strings at spaced intervals along the length of said strings,each said cross-over connection providing a fiovv passageinterconnecting said tubing strings for conducting lift gas from thetubing string into which lift gas is injected into said well into thetubing string through which well fluids are produced from said well; agas lift valve installed within the one of said tubing strings used forinjection or lift gas into said well at selected ones of said cross-overconnections for controlling flow of lift gas between said strings; eachof said gas lift valves having a central longitudinal bore communicatingwith said injection tubing string in which each said gas lift valve isinstalled and discharge ports for discharging lift gas from said centralflow passage into the cross-over connections at which each said valve issupported; and said central bore of each of said gas lift valves beingof a diameter and extending throughout the length of each of said valvesto permit movement of well tools through each said gas lift valve assaid well tools are moved along said tubing string in which said valvesare installed.

10. A well system for producing and servicing a well comprising: a firsttubing string supported in said well; a second tubing string supportedin said well extending in side-by-side substantially parallelrelationship with said first tubing string; one of said tubing stringsproviding a iiow passage for the recovery of well fluids from said well;the other of said tubing strings providing a flow passage for theinjection of lift gas into said well; said flow passages in said tubingstrings being isolated from an annular space around said tubing stringswithin said well; a plurality of cross-over connections included in saidtubing strings at spaced intervals along the length of said strings,each said cross-over connection providing a ow passage interconnectingsaid tubing strings for conducting lift gas from the tubing string intowhich lift gas is injected into said well into the tubing string throughwhich well fiuids are produced from said well; a gas lift valveinstalled within the one of said tubing strings used for injection oflift gas into said well at selected ones of said cross-over connectionsfor controlling the ow of lift gas between said strings; each of saidgas lift valves including a tubular mandrel provided with a longitudinalflow passage communicating with said tubing string in which saidinjection gas is introduced into said well and a plurality of ports foriiow of lift gas outwardly from said longitudinal flow passage; outerhousing means concentrically positioned in spaced relation around saidmandrel defining an annular space around said mandrel; means in saidannular space dividing said space into a dome gas chamber land anannular ilow passage communicating with said ports through said mandrelinto said central flow passage, said housing having port meanscommunicating with said annular ow passage for discharging lift gas fromsaid housing; an annular main valve member disposed in said annular iiowpassage and exposed on one side thereof to dome gas in said dome gaspressure chamber for biasing said valve member inwardly over said portsleading to said central flow passage, said valve Imember being adaptedto be displaced radially outwardly by lift gas pressure transmittedthrough said mandrel ports for expanding said valve member to releasegas from said central flow passage into said annular flow passage foriiow through said ports leading from said housing; and an annular checkvalve member disposed in said annular fiow passage between said housingports and said main Valve member to allow lift gas to tiow from saidmandrel ports to said housing ports and prevent backow of uids throughsaid annular flow passage from said housing ports to said mandrel ports.

11. A well system for producing and servicing a well comprising: a rsttubing string supported in said well; a second tubing string supportedin said well extending in side-by-side substantially parallelrelationship with said irst tubing string; one of said tubing stringsproviding a iiow passage for the recovery of well uids from said well;the other of said tubing strings providing a ow passage for theinjection of lift gas into said well; said tiow passages in said tubingstrings being isolated from an annular space around said tubing stringswithin said well; a plurality of cross-over connections included in saidtubing strings at spaced intervals along the length of said strings,each said cross-over connection providing a fiow passage interconnectingsaid tubing strings for conducting lift gas from said tubing string intowhich lift gas is injected into said well into said tubing stringthrough which well fluids are produced from said well; each of saidycross-over connections including a body mandrel provided with spacedlongitudinal first and second iiow passages and a transverse fiowpassage communicating said first and second iow passages, said bodymandrel being connectible at opposite ends with the conduits comprisingsaid first and second tubing strings whereby ow in one of said tubingstrings iiows through one of said longitudinal flow passages in saidcross-over connection and flow in the other of said tubing strings owsthrough the other of said longitudinal fiolw passages of said crossoverconnection; each of said cross-over connections including a slidingsleeve having ports therein disposed in a first of said flow passages ofsaid mandrel and movable longitudinally between one position at whichsaid first flow passage communicates with said transverse flow passageand another position at which said yfirst fiow passage is isolated fromsaid transverse passage; and a sliding sleeve having ports therein inthe other of said fiow passages of said body mandrel whereby saidlongitudinal iiow passages of said mandrel may be isolated from eachother by either of said sliding sleeves.

12. A well system in accordance with claim 11 including a gas lift valvedisposed in one of said sleeves at selected ones of said cross-overconnections.

13. A well system for producing and servicing a well comprising: a firsttubing string supported in said well; a second tubing string supportedin said well extending in side-by-side substantially parallelrelationship with said first tubing string; one of said tubing stringsproviding a fiow passage for the recovery of well fiuids from said well;the other of said tubing strings providing a flow passage for theinjection of lift gas into said well; said ow passages in said tubingstrings being isolated from an annular space around said tubing stringswithin said well; a plurality of cross-over connections included in saidtubing string at spaced intervals along the length of said strings, eachsaid cross-over connection providing a flow passage interconnecting saidtubing strings for conducting lift gas from the tubing string into whichlift gas is injected in said well into the tubing string through whichwell fiuids are produced from said well; each of said cross-overconnections comprising a body mandrel provided with spaced longitudinaltirst and second flow passages and a a transverse ow passagecommunicating said first and second flow passages, said mandrel beingconnectible at opposite ends with the conduits comprising said first andsecond tubing string whereby liow in one of said tubing strings flowsthrough one of said longitudinal iiow passages in said cross-overconnection and fiow in the other of said tubing strings fiows throughthe other of said longitudinal flow passages of said cross-overconnection; and an extensible swivel joint connected in each tubingstring section of one of said tubing strings between adjacent cross-overconnections in said well system.

14. A Well system as defined in claim 13 wherein said swivel jointcomprises telescopically disposed interconnected tubing members adaptedto be extended and retracted in sealed relationship for connecting eachsaid tubing string between said cross-over connections.

15. A well system as defined in claim 14 wherein said telescopicallyrelated tubular members are interconnected by threads having the samecharacteristics as threads connecting one end of one of said membersinto said tubing string section to provide identical travel ratesbetween said members and said end of said joint whereby said members areextended at a rate equal to the rate of threading said end of said jointinto said tubing string section.

16. A Well system as defined in claim 15 wherein one of saidtelescopically related tubular members is threaded over a substantialportion of its length and provided with seal means along an end portionof said member and Said other tubular member has a smooth surface over asubstantial length thereof engaged by said seal means over substantiallythe distance travel of said telescopically related members betweencontracted and extended relative positions of said members forpreventing leakage between said members as said members are extended andretracted and at any of the relative positions of said members betweenthe fully extended and fully retracted relationship of said members.

17. A well system for producing and servicing a well comprising: a firsttubing string supported in said well; a second tubing` string supportedin said well extending in side-by-side substantially parallelrelationship with said first tubing string; at least of one of saidtubing strings extending to a producing formation penetrated by saidwell and being adapted to direct well fluids from said formation throughsaid well to the surface end thereof; the other of said tubing stringsproviding for injection of lift gas into said well for recovery of wellfluids from said well; said first and second tubing strings providinglift gas injection and well production flow passages isolated from theannulus of said well around said tubing strings whereby lift gas isinjected into and fluids are produced from said well independently ofannulus conditions in said well; a plurality of cross-over assembliesconnected in said tubing strings at spaced intervals between the surfaceend of said well and said producing formation, each of said cross-overconnections including a transverse flow passage communicating said gasinjection flow and said well production flow passages of said tubingstrings; means connected between said tubing strings below the lowermostof said cross-over connections providing a flow passage between saidstrings to permit said strings to form a closed circuit flow path withinsaid well for pumping well tools to and from said cross-overconnections; a valve in said tubing string extending to said producingformation below the interconnection of said tubing strings to allow wellfluids to flow upwardly in said tubing string while preventing backflowof well fluids through said tubing string toward said producingformation; and a surface installation connected with said tubing stringsfor pumping well fluids into either of said tubing strings whilereceiving well fluid returns from the other of said tubing strings.

18. A well system as dened in claim 17 including a gas lift valve atselected cross-over connections for controlling flow of lift gas betweensaid tubing strings whereby lift gas is injected into said well in oneof said tubing strings and well fluids are produced from said well inthe other of said tubing strings.

19. A well system for producing and servicing a well comprising: a firsttubing string supported in said well; a second tubing string supportedin said well extending along said first tubing string; at least one ofsaid tubing strings extending to a producing formation penetrated bysaid well and adapted to direct well fluids from said formation throughsaid well to the surface end thereof; the other of said tubing stringsproviding for injection of lift gas into said well for recoveryof wellfluids from said Well; a plurality of cross-over assemblies connected insaid tubing strings at spaced intervals between the surface end of saidwell and said producing formation, each of said cross-over assembliesincluding a transverse flow passage communicating said tubing strings; agas lift valve supported in said tubing string providing for injectionof lift gas at selected cross-over assemblies for controlling flow oflift gas between said tubing strings whereby lift gas is injected intosaid well in one of said tubing strings and well fluids are producedfrom said well in the other of said tubing strings; means connectedbetween said tubing strings below the lowermost of said cross-overassemblies providing a flow passage between said strings to permit saidtubing strings to form a closed circuit flow path within said well forpumping well tools to and from said cross-over assemblies; a valve insaid tubing string extending to said producing formation below theinterconnection of said tubing strings to allow well fluids to flowupwardly in said tubing string while preventing backflow of well fluidsthrough said tubing string toward said producing formation; and asurface installation connected with said tubing strings for pumping wellfluids into either of said tubing strings while receiving well fluidsfrom the other of said tubing strings.

20. A well system for producing and servicing a well comprising: a firsttubing string supported in said well; a second tubing string supportedin said well extending along said first tubing string; at least one ofsaid tubing strings extending to a producing formation penetrated bysaid Well and being adapted to direct well fluids from said formationthrough said well to the surface end thereof; the other of said tubingstrings providing for injection of lift gas into said well for recoveryof well fluids from said well; a plurality of cross-over assembliesconnected in said tubing strings at spaced intervals between the surfaceend of said well and said producing formation, each of said cross-overassemblies including a transverse flow passage communicating said tubingstrings; each of said cross-over assemblies including at least onesleeve valve movable between a first position for isolating said tubingstrings from each other through said lateral flow passage of saidcross-over assemblies and a second position for permitting said tubingstring to communicate with each other through said lateral flow passage;a gas lift valve at selected cross-over assemblies for controlling flowof lift gas between said tubing strings whereby lift gas is injectedinto said well in one of said tubing strings and well fluids areproduced from said well in the other of said tubing strings; meansconnected between said tubing strings below the lowermost of saidcross-over assemblies providing a flow passage between said strings topermit said tubing strings to form a closed circuit flow path withinsaid well for pumping well tools to and from said cross-over assemblies;a valve in said tubing string extending to said producing formationbelow the interconnection of said tubing strings to allow well fluids toflow upwardly in said tubing string while preventing backflow of wellfluids through said tubing string toward said producing formation; and asurface installation connected with said tubing strings for pumping wellfluids into either of said tubing strings while receiving well fluidreturns from the other of said tubing strings.

21. A well system comprising: means comprising a first tubing stringproviding a first flow passage along a well; means comprising a secondtubing string providing a second flow passage along said well; meansconnecting said tubing strings providing a cross-over passage betweenthe first and second flow passages within said well; each of said tubingstrings being provided with a locking recess for a well tool lockingmandrel for locking a well tool in either of said tubing strings at saidcross over passage; and a sliding sleeve valve provided in each of saidtubing strings, said valve being movable between open and closedpositions for controlling communication between said tubing stringsthrough said cross-over passage.

22. A well system for servicin'g a well comprising: a first tubingstring supported in said well; a second tubing string supported in saidwell extending along said first tubing string; one of said tubingstrings providing a flow passage for the recovery of well fluids fromsaid well; the other of said tubing strings providing a flow passage forthe injection of lift gas into said well; a plurality of cross-overconnections included in said tubing strings at spaced intervals alongthe length of said strings, each providing a flow passageinterconnecting said tubing strings for conducting lift gas from thetubing string in which lift gas is injected into said well into thetubing string in which well fluids are produced from said well; a gaslift valve installed in said string in which litt gas is injected atselected ones of said cross-over connections for controlling the flow oflift gas between said strings; each of said gas lift valves comprising atubular mandrel provided with a longitudinal ow passage and a pluralityof ports for flow of lift gas outwardly from said longitudinal owpassage, outer housing means concentrically positioned in spacedrelationship around said mandrel dening an annular space around saidmandrel, means in said annular space dividing said space into a dome gaschamber and an annular ow passage communicating with said ports throughsaid mandrel in said central flow passage, said housing having portmeans communicating with said annular ow passage for discharging liftgas from said housing, an annular main valve member disposed in saidannular flow passage and exposed on one side thereof to dome gas in saiddome gas pressure chamber for biasing said valve member inwardly oversaid ports leading to said central passa-ge, said valve member beingadapted to be displaced radially outwardly by lift gas pressuretransmitted through said mandrel ports for expanding said valve memberto release gas from said central ow passage into said annular flowpassage for flow through said passage away from said housing, and anannular check valve member disposed in said annular flow passage betweensaid housing ports and said main valve member to allow lift gas to flowfrom said mandrel to said housing ports and prevent backow of fluidsthrough said annular flow passage from said housing ports to saidmandrel ports.

23. A well system for producing and servicing a well comprising: a rsttubing string supported in said well; a second tubing string supportedin said well extending along said rst tubing string; one of said tubingstrings extending to a producing formation penetrated by said well todirect well uids from said formation to the surface end of said well;the other of said tubing strings providing for gas lift injection intosaid well for recovery of well fluid therefrom; cross-over meansconnected in said tubing strings including a transverse flow passagecommunicating said tubing strings; means for connecting said tubingstrings below said cross-over means to permit said tubing strings toform a closed circuit ow path within said well for pumping said welltools to and from said cross-over means; and a surface installationconnected with said tubing strings for pumping uids into either of saidtubing strings while receiving return uids from the said other of saidtubing strings.

24. A well system in accordance with claim 23 including gas lift valvemeans supported at said cross-over means in said tubing string employedfor injection of lift gas to said well for controlling the admission oflift lgas to said transverse flow passage leading to said tubing stringextending to said producing formation.

25. A well system in accordance with claim 23 including gas lift valvemeans supported at said cross-over means in said tubing string extendingto said producing formation for admitting gas from said transverse flowpassage into said tubing string extending to said producing formation.

26. A well system in accordance with claim 19 including sleeve valvemeans in each of said cross-over connections, said sleeve valve meansbeing movable between open and closed positions communicating saidtubing strings with each other.

References Cited UNITED STATES PATENTS 2,806,429 9/1957 Anderson et al103-233X 3,208,533 9/1965 Corley, Jr 166-313X 3,212,450 10/1965Castellot 103-260 3,334,690 8/1967 Garrett 103-233X 3,357,492 12/1967Hubby 166-313X 3,419,074 12/1968 Brown 103-233X 3,050,121 8/1962 Barrettet al 4l7-109X CARLTON R. CROYLE, Primary Examiner R. E. GLUCK,Assistant Examiner U.S. Cl. X,R. 166-313

